When milking an animal by using an automated milking system, the milk is drawn from the teats of the animal by means of teat cups connected to vacuum. The milk is drawn through a milk tube and into a flow meter wherein the amount of milk is measured. The milk is further transported to a storing tank or similar wherein it is stored together with milk from other animals while waiting for a milk lorry to collect it.
On regular time basis, e.g. once a month, a sample of the milk from each animal is taken, which sample is typically sent to a laboratory for analysis, in which various parameters such as contents of fat, protein, cell, and urea are examined. It is expensive to implement the analysis at the milk sampling device and further, the laboratory equipment necessary is space demanding, thus samples are typically taken and sent to a laboratory. Possibly, some kind of simpler measurements could be introduced at the milk sampling device.
The milk sampling is typically performed in connection with milking of the animals by employing a milk sampling device provided with a fixed or removable cassette wherein milk test tubes can be placed, and with a filling member connected to the milking system and capable of filling the respective tubes with milk from the respective animals. When all the tubes are filled they are removed from the milk sampling device, either manually one by one, or by means of removing the complete cassette, and sent to the laboratory.
The laboratory equipment is adapted to the cassettes and test tubes that are used by the farmers served by that laboratory. Further, laboratory equipment, cassettes and test tubes, vary quite much from country to country.
Further, the sample tubes are typically prepared with a preservative prior to milk sampling, which preservative shall restrain the milk from turning to sour before the samples have been delivered to the laboratory and been analyzed. This preservative is to be dissolved in the milk, which typically takes a period of time, during which the increase of bacteria in the milk speeds up, whereby the risk that the milk turns to sour increases.
One prior art milk sampling device is disclosed in EP 0 564 023 A1 (LELY/MAASLAND). This device is provided with a cassette formed as a rotating box in which, along its circumference, milk sample collecting elements can be arranged. The filling member is disposed in a fixed position, while the collecting elements can be placed successively under the filling member. The filling member is further provided with a vertically movable type of injection needle to be inserted into the collecting elements. In this construction, the cassette and the injection needle have to be moved synchronously, which requires specific measures to be taken.
Besides, in case of a relatively large number of collecting elements, the space in the box is insufficiently utilized. Therefore, the cassette occupies relatively much space, which in view of the extensive equipment present in milking systems of today, is experienced as a drawback.
Another prior art milk sampling device is depicted in EP 0 749 681 A1 (LELY/MAASLAND). This device is provided with a removable cassette in which milk sample collecting elements can be placed, and at least one filling member capable of being placed successively above various collecting elements and bringing milk samples, taken from milk provided by an automatic milking machine, to the respective collecting elements. Guide means is provided for supporting the filling member such that the filling member is moved, by successively increasing and decreasing the distance between the guide means and the cassette, from a position above a collecting element to an adjacent position above a nearby situated collecting element. In such manner the filling member may step from collecting element to collecting element along a predetermined fixed zigzag formed closed path.
This device has a simple design, but the movement of the filling member is not flexible since it is determined by said fixed path. This may be a major drawback if a single collecting element is to be used for collecting a second non-consecutive sample, e.g. for sampling a cow a second time a number of hours later, as the guide means may have to step through a relatively long path before reaching the collecting element in question.
A further drawback of both these prior art milk sampling devices is that they are designed to fit only one cassette size. As there exist different standards of cassettes and sample collecting elements in different countries a device has to be manufactured in various designs if it is to be put on several markets.
Further, there is a certain risk of mixing samples at the milking farm, during transport, or at the laboratory since the individual sample collecting elements are only identified through their respective positions in the cassette.
If the individual sample collecting elements are removed from the cassette of the milk sampling device and placed in other cassette or box for being dispatched to the laboratory, this risk of mixing samples is considerably increased as well as such an approach is time consuming, labor intensive and thus costly.
Further, the above-mentioned documents neither address the apparent problem that the milk samples may turn to sour before reaching the laboratory nor discuss the dissolving of a preservative in the milk samples.